Shulchan Arukh Orach Chayim · Siman 234

English

One who wishes to pray both Minchah Gedolah and Minchah Ketanah. This siman contains two se'ifim. One who wishes to pray both Minchah Gedolah and Minchah Ketanah should designate only Minchah Gedolah as a voluntary prayer. If he prays Minchah Gedolah as obligatory, he may pray Minchah Ketanah only as a voluntary prayer. However, it is not fitting to offer a voluntary prayer unless he knows himself to be careful and diligent, and judges himself capable of maintaining concentration in his prayer from beginning to end without distraction. But if he does not concentrate properly during it, we apply to him the verse, ‘What need have I of your many sacrifices?’ Rema: Ashrei preceding Minchah should be recited only when a minyan is present in the synagogue, so that they may recite over it the Kaddish preceding the Minchah prayer (Hagahot Semak and Kol Bo). Some have written that the custom is to recite the passage concerning the daily offering before Ashrei of the Minchah prayer, corresponding to the daily offering of the afternoon; this is a fine custom (Abudarham in the name of the Ri, and Beit Yosef).

English

If one forgot and did not pray Minchah, he prays the evening Amidah twice and recites Ashrei before the prayer that serves as tashlumin (a compensatory prayer) for the missed Minchah prayer (see above, siman 108).